In this work, a classical approach was used for calibrating the GESPECOR detector model for computing the full-energy peak efficiency of p-type coaxial HPGe detectors that is based on the use of ...linear least squares optimization. The key element of the work is the multiplicative model developed for approximating the values of the full-energy peak efficiency provided by GESPECOR code. It was linearized using the logarithmic transformation to allow an easy use of the linear least squares optimization. A procedure was also developed to estimate the optimal values of the parameters, describing the p-type coaxial HPGe detectors. Its application to a Canberra detector GC3018 showed that it is possible to determine accurate values of the full-energy peak efficiency computed by GESPECOR code using the optimized parameter values.
A novel virtual point detector model was developed for cylindrical high purity germanium detectors that are widely used in gamma-ray spectrometry. According to this model, the full energy peak ...efficiency response of these detectors can be computed by replacing the detector with a virtual point detector located at the center of the detector crystal. In fact, the novel model makes the transfer of the FEP efficiency response from a reference point source to a given point source, both sources being located on a line that passes through the virtual point detector. The model was tested and provided accurate results.
•A novel virtual point detector model is described in this paper.•The FEP efficiency response is approximated by a power function model.•The novel model has a solid theoretical basis.•Two computational ways were developed to apply in practice the model.•This model may provide accurate values of the FEP efficiency response.
In this paper there are described three different algorithms of Minimum Detectable Activity (MDA) calculus, and its use in high resolution gamma spectrometry. In the first part, few introductive ...theoretical aspects related to the MDA are presented. Further, the theory was applied to real gamma rays spectrometry measurements and the results were compared with the activities reference values. Two different gamma spectrometry systems, both of them using High Purity Germanium (HPGe) detectors, but having different efficiencies, were used. Samples having different geometries and radionuclides content were measured. The measured samples were made by dissolving of some acids containing anthropogenic radionuclides in water, obtaining a density of 1g/cm3. Choosing this type of matrix was done because of its high homogeneity.
•Three different MDA algorithms were applied to gamma spectrometry measurements.•The measurements were performed using two HPGe detectors.•MDA performances of the two spectrometric systems were compared.•The measured samples had different geometries and contained a mixture of radionuclides.•MDA was studied also as a function of measuring time.
Copper deficiency can cause bone lesions in infants, which might be confused with child abuse. Two extremely low birth weight preterm infants had complicated medical courses requiring prolonged ...parenteral nutrition for short-gut syndrome, which led to the development of cholestasis. Both had spent their entire lives in the hospital. They had been on prolonged ventilator support for chronic lung disease. They developed signs of copper deficiency between 5 and 6 months of age, initially raising child abuse concerns. Musculoskeletal discomfort led to the recognition of radiographic findings of metabolic bone disease. Included were osteoporosis, metaphyseal changes, and physeal disruptions. Copper levels were low; both low copper parenteral nutrition and gut losses from refeeding diarrhea likely contributed to their deficiency. Therapeutic supplementation with copper corrected their deficits and clinical and radiologic findings. The information from these cases, in particular, their radiologic findings, indicate the need to monitor copper status in at-risk premature infants. These findings may aid prevention and earlier recognition of copper deficiency. Their specific radiologic and clinical findings should aid differentiation of such children from abused infants.
We assessed the efficacy of nonpharmacologic techniques to prevent postoperative nausea and vomiting (PONV) by systematic review. These studies included acupuncture, electroacupuncture, ...transcutaneous electrical nerve stimulation, acupoint stimulation, and acupressure. Of the 24 randomized trials retrieved by a search of articles indexed on the MEDLINE and EMBASE databases (1980-1997), 19 were eligible for meta-analysis. The primary outcomes were the incidence of nausea, vomiting, or both 0-6 h (early efficacy) or 0-48 h (late efficacy) after surgery. The pooled relative risk (RR) and numbers needed to treat (NNT) were calculated. In children, no benefit was found. Some results in adults were significant. Nonpharmacologic techniques were similar to antiemetics in preventing early vomiting (RR = 0.89 95% confidence interval 0.47-1.67; NNT = 63 10-infinity) and late vomiting (RR = 0.80 0.35-1.81; NNT = 25 5-infinity) in adults. Nonpharmacologic techniques were better than placebo at preventing early nausea (RR = 0.34 0.20-0.58; NNT = 4 3-6) and early vomiting in adults (RR = 0.47 0.34-0.64; NNT = 5 4-8). Nonpharmacologic techniques were similar to placebo in preventing late vomiting in adults (RR = 0.81 0.46-1.42; NNT = 14 6-infinity). Using nonpharmacologic techniques, 20%-25% of adults will not have early PONV compared with placebo. It may be an alternative to receiving no treatment or first-line antiemetics.
This systematic review showed that nonpharmacologic techniques were equivalent to commonly used antiemetic drugs in preventing vomiting after surgery. Nonpharmacologic techniques were more effective than placebo in preventing nausea and vomiting within 6 h of surgery in adults, but there was no benefit in children.
Two dedicated software packages -LabSOCS and GESPECOR- for efficiency evaluation in gamma-ray spectrometry, were compared for equivalence. The detection efficiency and the coincidence-summing ...corrections coefficients were calculated for a specific HPGe detector, for different sample parameters and energies typically encountered in environmental radioactivity measurements. The discrepancy between the results obtained with the two codes were acceptable for most of the applications. Furthermore, the deviations between the values of the standard sources/ reference materials activities from the certificate and the values obtained after Monte Carlo simulation were less than 8% for LabSOCS and 9% for GESPECOR.
•LabSOCS and GESPECOR were compared for equivalence.•Detector characterization is absolutely necessary for simulation with LabSOCS.•Detection efficiencies were evaluated both with LabSOCS and GESPECOR for volume sources.•Coincidence summing effects were evaluated for multi-energetic radionuclides.•Results demonstrate precision and accuracy of both software.
The Radioactive Waste Management Department from IFIN-HH, Bucharest, performs the conditioning of the institutional radioactive waste in concrete matrix, in 200l drums with concrete shield, for final ...disposal at DNDR – Baita, Bihor county, in an old exhausted uranium mine. This paper presents a gamma-ray spectrometry method for the characterization of the radioactive waste drums' radionuclides content, for final disposal. In order to study the accuracy of the method, a similar concrete matrix with Portland cement in a 200l drum was used.
•An equivalent matrix of a 100l radwaste cemented in a 200l drum was measured.•Vertical channels for hosting standard sources were drilled in the concrete matrix.•Drum was measured with 152Eu sources placed in different configurations in channels.•Activity was calculated assuming a homogeneous radioactive matrix.•For photons with E>444keV computed activity is relatively close to certified value.
A method is presented for calculating the expected number of counts in peaks that have a large relative peak-area uncertainty and appear in measured gamma-ray spectra. The method was applied to ...calculations of the correction factors for peaks occurring in the spectra of radon daughters. It was shown that the factors used for correcting the calculated peak areas to their expected values decrease with an increasing relative peak-area uncertainty. The accuracy of taking the systematic influence inducing the correction factors into account is given by the dispersion of the correction factors corresponding to specific peaks. It was shown that the highest accuracy is obtained in the peak analyses with the GammaVision and Gamma-W software.
•The results of peak analysis programs were tested on a statistical basis.•Peak areas with a large statistical uncertainty were tested for their trueness.•The test was performed on five different programs for analyzing the spectra.•It was found that peak areas with a large statistical uncertainty are too large.•A way, how to calculate uncertainty-dependent correction factors is described.
The neonatal period is classically described as the first 28 days of life, but owing to the fact that changes in skeletal tissue occur at a somewhat slower pace than those of other organ systems, ...events of the first few months are considered herein. Neonatal bone health is a problem of growing interest and concern because of the increasing recognition of its impact upon childhood, adolescent and even adult bone health. Osteoporosis in adulthood often has its roots in childhood and some forms may be prevented by proper attention to neonatal and childhood bone health. The premature infant likely suffers lifelong decreased bone mineral density as a result of its early birth and lack of adequate mineral stores that are typically present in full-term infants. Adequate embryogenesis, growth and development of the skeletal system are multifactorial and under the influence of a host of genes, growth factors and enzymes. The evaluation of skeletal dysplasias and their recognition are beyond the scope of this paper and will not be considered in this discussion. Here the focus will be on the adequacy of mineralization and metabolic aspects of the growth and development of the fetal and neonatal skeleton, the effect of birth, both preterm and term, maternal illness and health as well as infant diseases.
Postoperative nausea and vomiting (PONV) are common complications following surgery and anaesthesia. Drug therapy to prevent PONV is only partially effective. An alternative approach is to stimulate ...a P6 acupoint on the wrist. Although there are many trials examining this technique, the results are conflicting.
To determine the efficacy and safety of P6 acupoint stimulation in preventing PONV.
We searched CENTRAL (The Cochrane Library, Issue 1, 2003), MEDLINE (January 1966 to January 2003), EMBASE (January 1988 to January 2003) and the National Library of Medicine publication list of acupuncture studies up to and including January 2003. Reference lists of retrieved papers and reviews were consulted for additional references.
All randomized trials of techniques that stimulated the P6 acupoint compared with: sham treatment or drug therapy for the prevention of PONV. Interventions used in these trials included acupuncture, electro-acupuncture, transcutaneous nerve stimulation, laser stimulation, acustimulation device and acupressure.
Two reviewers independently assessed methodological quality and extracted the data. Primary outcomes were incidences of nausea and vomiting. Secondary outcomes were the need for rescue antiemetic therapy and adverse effects. A random effects model was used and relative risk (RR) with associated 95% confidence intervals (95% CI) are reported. Egger's test was used to measure the asymmetry of the funnel plot.
Twenty-six trials (n = 3347) were included, none of which reported adequate allocation concealment. There were significant reductions in the risks of nausea (RR 0.72, 95% CI 0.59 to 0.89), vomiting (RR 0.71, 95% CI 0.56 to 0.91) and the need for rescue antiemetics (RR 0.76, 95% CI 0.58 to 1.00) in the P6 acupoint stimulation group compared with the sham treatment, although many of the trials were heterogeneous. There was no evidence of difference in the risk of nausea and vomiting in the P6 acupoint stimulation group versus individual antiemetic groups. However, when different antiemetics were pooled, there was significant reduction in the risk of nausea but not vomiting in the P6 acupoint stimulation group compared with the antiemetic group (RR 0.70, 95% CI 0.50 to 0.98; RR 0.92, 95% CI 0.65 to 1.29 respectively). The side effects associated with P6 acupoint stimulation were minor. There was some evidence of asymmetry of the funnel plot.
This systematic review supports the use of P6 acupoint stimulation in patients without antiemetic prophylaxis. Compared with antiemetic prophylaxis, P6 acupoint stimulation seems to reduce the risk of nausea but not vomiting.
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